*SetFieldForce() - symmetric field pair
Sets the force properties of a symmetric field pair.
Syntax
*SetFieldForce(field_name, LEFT|RIGHT, 
                                     f_x, f_y, f_z, 
                                     t_x, t_y, t_z)
    Arguments
- field_name
 - The variable name of an existing field pair.
 - LEFT RIGHT
 - If LEFT is specified, the properties are assigned to the left field, and the right field properties are made symmetric to the left field.
 - f_x, f_y, f_z
 - The force values at the lengths length_x, length_y, and length_z, respectively.
 - t_x, t_y, t_z
 - The torque values at the lengths length_rx, length_ry, and length_rz, respectively.